The present invention relates to a radiation thermometer for detecting the thermal radiation of an object placed in a plasma to determine the temperature of the object, a sputtering apparatus using the radiation thermometer for manufacturing semiconductor devices, and a method of measuring the temperature of an object by using radiation.
Various kinds of radiation thermometers have been known which include a monochromatic radiation thermometer for determining the temperature of an object to be measured by measuring the intensity of radiation emitted from the to-be-measured object (that is, energy emitted from the object), and a two-wavelength radiation thermometer for determining the temperature of an object to be measured from a ratio of the intensity of one of two wavelength components of radiation to the intensity of the other wavelength component.
Technology relating to radiation thermometers of this kind is disclosed in a Japanese patent application Post-Exam. Publn. No. Sho 60-58411 (JP-B-60-58411) and a Japanese patent application Post-Exam. Publn. No. Sho 60-58412 (JP-B-60-58412).
According to the prior art, in a case where a radiator such as a plasma is present in the vicinity of an object to be measured, the intensity of plasma light is added to the intensity of thermal radiation emitted from the to-be-measured object, and thus it is difficult to determine the correct temperature of the to-be-measured object.
Further, since the correct temperature cannot be determined, it is impossible to exactly measure the temperature distribution on the surface of an object to be measured. In a plasma processing apparatus, it is very important for the fabrication of semiconductor devices to exactly measure the temperature distribution on the surface of a wafer to be measured.